Tubular steel culverts are well-known in the art and are commonly employed as an underground conduit for water. A long-recognized shortcoming of conduits of this nature and others constructed from different types of material, is that the extremities of the culverts are susceptible to breakage or deformation as a result of increased loading in this area. This normally is attributable to the weight of traversing vehicles travelling over culverts which have not been buried deeply.
A further shortcoming of tubular culverts, no matter what their cross-sectional shape may be, is the collection of unwanted debris at the culvert ends which impedes the flow of water and which commonly results from material in the slope or embankment, through which the culvert extends, collecting at the lower portion of the water inlet or discharge ends of the culvert. In situations where embankment subsistence is regarded as a problem that must be addressed, a common practice is to reinforce the embankment area surrounding the free ends of the conduit by a retaining wall formed from stonework, wire mesh or the like.
Parker, in U.S. Pat. No. 546,245, issued Sep. 10, 1889, discloses a sectionalized tubular culvert or pipe conduit with provision, at the exterior ends of the culvert or pipe, for providing for a retaining wall constructed from sectionalized end wall sections, including sections which interlock with the grooves provided in the exterior ends of the conduit. A variation on this is also disclosed by Parker in U.S. Pat. No. 567,653, issued Sep. 15, 1898. In yet another variation, Simpson, in U.S. Pat. No. 786,059, issued Mar. 28, 1905, discloses an arched subway structure constructed from semi-circular shell sections and which, at its free ends, is provided with an outwardly-projecting semi-circular flange, and against the interior face of which, reinforcing wall sections abut.
While the foregoing prior art references are also representative of other types of retaining walls used with conduits, tunnels or the like, they are not concerned with protecting the end portion of a conduit which, as a result of its installation or location, is exposed to periodic loading which can break, or in the case of metal culverts, deform at the ends of the culvert, and which can also result in the collection of unwanted debris in the inlet and discharge areas of the culvert.